This invention relates to mining shovels, and more particularly to a swing drive assembly fixed to a mining shovel frame to rotatably drive the frame relative to a mining shovel base.
A conventional mining shovel generally includes a base supported by ground engaging tracks. The base rotatably supports a frame on which is mounted a housing for protecting mining shovel components, such as power generation equipment, electrical equipment, a dipper hoist, and controls. The frame rotates about a pintle relative to the base. The frame is rotatably driven by one or more swing drives. In a known mining shovel, the swing drive is welded to the frame. Other designs bolt the swing drive directly to the frame.
As the frame rotates relative to the base, it deflects which imposes severe stress on the swing drive. The stress can cause the welds fixing the swing drive to the frame to fail, or the bolts affixing the swing drive to loosen, which results in downtime for the shovel to make repairs. A need exists for a swing drive assembly which does not fail as a result of stresses caused by frame deflection.
The present invention provides a swing drive assembly for use with a mining shovel having a frame rotatable relative to a base, wherein the swing drive assembly is fixed to the frame and engages a ring gear fixed to the base to rotatably drive the mining shovel frame relative to the mining shovel base. The assembly includes a swing girder having a top wall and bottom wall joined by a back wall. At least one strut having a top end extends upwardly from the top wall, and an attachment point is proximal said strut top end for fixing the swing drive assembly to the frame. At least one attachment point is proximal one end of the top wall, and at least one attachment point is proximal an opposing end of the top wall, wherein the girder is fixable to a mining shovel frame at each of the attachment points. Preferably, each attachment point is fixed to the mining shovel frame with at least one bolt. Most preferably, the swing girder is mounted to the frame, and hangs below the frame to engage the ring gear.
A general objective of the present invention is to provide a swing drive assembly having a swing girder which can withstand the stresses caused by the mining shovel frame rotating relative to the base. The first, second, and third attachment points define a novel three point mounting system for attaching the swing girder to the frame, and allows the girder to flex with the frame deflections.
Another objective of the present invention is to provide a swing girder which is easily manufactured and fixed to the mining shovel frame. The multipoint mounting system assures alignment, as only three points establish a plane. Moreover, the multi point mounting system minimizes the amount of machining required prior to assembly to further simplify alignment. Prior art swing girders required machining of the entire perimeter of the girder abutting the frame. A three point mounting system only requires machining the mounting pads at each attachment point.
Yet another objective of the present invention is to reduce shafting and bearing loading. This objective is accomplished by hanging a portion of the swing drive assembly below the frame and supporting the pinion shafts on both sides of the pinion. Hanging a portion of the swing drive assembly below the frame requires a shorter pinion shaft which can be straddle mounted, thus reducing shafting and bearing loading.
The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention.